Cottonseed detection

For cottonseeds, pyrithiobac-sodium is extracted with acetone-water (4 1, v/v). After filtration, the acetone is removed by evaporation under reduced pressure. The residue is adjusted to pH 1 and extracted with ethyl acetate. The extract is cleaned up by liquid-liquid partitioning and methylated with diazomethane. The methyl ester of pyrithiobac is purified by silica gel column chromatography. Pyrithiobac-methyl is determined by gas chromatography (GC) with nitrogen-phosphorus detection (NPD). 

A protocol approved by the FDA to determine the safety of low gossypol cottonseed kernels for human consumption was the basis for the second study by Reber (7 ). To prepare raw cottonseed flour, raw kernels were ground to meet Ro-tap sieve specifications of lab chow. To prepare roasted cottonseed flour, raw kernels were dry roasted at not less than 121°C for not less than 5 min. To prepare cooked cottonseed flour, raw kernels were cooked in steam until batch temperature had been at or above 121°C for 5 min. All cottonseed kernels were ground in the manner described above. The kernels contained not more than 0.037% (370 ppm) of free gossypol. They were free of Salmonella and did not contain detectable amounts of aflatoxin. The proximate analyses of the cottonseed flours are shown in Table I. 

Brown and coworkers (18,35) used X-ray fluorescence to analyze the elemental composition of total dusts from five cottonseed oil mills. The dusts were removed from high volume samplers by forceps followed by brushing. Samples from cleaning, delintering, hulling and baling areas were taken. A summary of the data is shown in Table XIV. Silicon is the most abundant element detected in all areas except hulling. 

Aflatoxins are potent carcinogenic, mutagenic and teratogenic metabolites produced by molds. The major food affected with aflatoxins are corn, peanuts, rice, cottonseeds, dried fruit and milk from ingestion (103). The US action standards established by FDA are 20 pg/Kg for foods consumed by humans and 0.5 pg/kg for milk. In the case of animal feed, the levels are from 100 to 300 pg/kg. Therefore, assays capable of detecting at these levels have to be developed, (see Table 1 (104,105)). Detection of aflatoxins entails conjugation of these small molecules with carrier proteins like bovine serum albumin to produce antibodies (20). A number of commercial kits for aflatoxins are available (see sections on kits and immunoaflinity purification). 

Some of the tests involved relatively simple colour reactions such as the Baudouin reaction for sesame oil, and the Halphen test for cottonseed oil. In both cases a compound characteristic to an oil is used to determine the presence of the oil. Here again the test detected a component that today would be detected and quantified by gas chromatography (GC) or high performance liquid chromatography (HPLC). It was even possible to determine the presence of cholesterol or phytosterols, although, after separation, the identification as to which type was present depended on microscopic examination and fractional... 

Halphen Test for Detecting Cottonseed Oil (Cb 1-25) estimates the presence of cottonseed oil in vegetable or animal fats or oils as the result of a pink color formed between the reagent and cyclopropenoic fatty acids (sterculic and malvalic) normally present in cottonseed oil. 

Communities in India may also be exposed to hazardous cotton pesticides through the contamination of cottonseed and cottonseed derivatives - an important source of edible oil. Because of the intensive use of hazardous pesticides in cotton production much of the cottonseed oil entering the Indian food chain may be heavily contaminated . One analysis of cottonseeds collected from 5 locations in Punjab found detectable residues of the cotton pesticides ethion (WHO II), cypermethrin (WHO II), endosulfan (WHO II), chlorpyrifos (WHO II) the latter being 2 of the most common pesticides applied to cotton in India ... 

With US 51 million applied to cotton each year, methamidophos - a neurotoxin that impairs the activity of key enzymes essential for the normal transmission of nerve impulses - is the fourth most significant pesticide applied to cotton worldwide . Cotton accounts for over 40% of global use . Methamidophos residues have been detected in cottonseed and derivatives and may pose a particular hazard to those who consume cottonseed oil, or who feed derivatives to livestock . In laboratory experiments, hens and goats reared with food containing methamidophos showed traces of the pesticide in their eggs and milk . 

Adulteration of fats and oils is an old problem. Many older tests involved determination of physical properties such as refractive index, melting point, and viscosity. However, color tests were later used for this purpose. Thus, Baudonin reaction for sesame oil and the Halpben test for cottonseed oil have been noted. In both cases, a compound characteristic to an oil determines the presence of the oil. However, today such detections and quantitations are carried out with GC and HPLC procedures. Thus, cholesterol and phytosterols may be determined by gas chromatography for fingerprinting purposes however, fatty acid analysis might also be used for higher levels of contamination (31). Detailed discussion of issues related to oil authentication and adulteration has taken place (11). 

Halphen Reaction. The halphen test is a very sensitive and reliable method for detecting the presence of cottonseed oil in another oil. A reaction with sulfur in carbon disulfide mixed with equal amounts of amyl alcohol gives a cherry red color when cyclopropenoid fatty acids unique to the Malvacae family, which includes cottonseed and okra, are present. This test is capable of detecting 0.25% or less cottonseed oil in an oil blend. The oil is no longer responsive to the halphen test after hydrogenation, which decreases the iodine value 2-5 units. 

Aflatoxins have been detected in milk, cheese, corn and other cereals, peanuts, cottonseed, nuts, figs and other foodstuffs. Milk and milk products, eggs and meat products are sometimes contaminated (generally with aflatoxins Ml and M2) because of the animals consumption of aflatoxin-contaminated feed. 

Because of unfavorable sorption effects on paper that cause tailing, materials with lower adsorptivity were sought. Thus, cellulose acetate [35] and nitrocellulose [36,37] membranes were introduced. Cellulose acetate can be either prepared in the laboratory by treating cellulose with acetic anhydride, or it may be purchased from commercial sources. Cellulose acetate membranes are readily soluble in phenol, glacial acetic acid, dichloromethane and acetone. In part they can be solubilized in several solvent mixtures e.g., chloroform/ethanol (9 1 v/v). For detection (optical scanning) the foil can be made translucent by immersion in cottonseed oil, decalin, liquid paraffin or Whitemore oil 120. 

In contrast to other investigators, Chen et al. (1965) were unable to detect an increase of linoleic acid with a dietary supplement of 10% flax oil or cottonseed oil. The discrepancy can be explained by the fact that at 44% the content of linoleic... 

Olive oil is often illegally adulterated with other less expensive vegetable oils. Oils widely used for this purpose include olive pomace oil, corn oil, peanut oil, cottonseed oil, sunflower oil, soybean oil, and poppy seed oil. °° Among the varions chemical and physical methods employed toward the detection of the adulteration of olive oil by low-grade olive oils and seed oils are (a) Sterol analysis (presence of stigmasterol and 3-sitosterol), (b) alkane analysis (C27, C29, and C31), (c) wax and aliphatic alcohol analysis, (d) fatty acids/(with HPLC) trans fatty acid, and (e) Triacylglycerol. 

In the infra-red (IR) spectrum a band at 1010 cm characteristic of the cyclopropene system has been used to determine high levels of cyclopropene acids (Bailey, Boudreaux and Skau, 1965). There is another specific band at 1870 cm" which is weak in the IR spectrum but intense in the Raman spectrum (Kint et aL, 1981). Using peak height ratios of this band relative to that at 1745 cm (for triacylglycerol carbonyls), quantification of cyclopropene acids down to 0.03% was possible. The method may have potential for detecting vegetable oil contamination with, for example, cottonseed oil, but information is needed on its accuracy and precision. 

Because of its high nutritional value and the beneficial effects that some of its compounds exert, the price of VOO is relatively higher if we compare it with other edible oils. This fact could explain why so many adulterations have been found for VOO this matrix is susceptible to adulteration with cheaper olive oil categories (olive oil pomace, refined olive oil) and/or other edible oils. Com, cottonseed, canola, palm, peanut, soybean, and sunflower oils have been detected in adnlterated VOOs. 

Becchi-Millian test n. Sensitive test for cottonseed oil. If cottonseed fatty acids are dissolved in 90% ethyl alcohol and a little dilute silver nitrate solution added, they separate, colored brownish or black, as the alcohol is boiled away on heating. It is claimed that as little as 1% of cottonseed oil is detected in a mixture by this test. 

The volatiles derived from oils containing hnolenic acid (soybean and canola oils) have significant sensory impact and lower threshold values than the volatiles derived from oils containing linoleic acid (cottonseed, com and sunflower oils) (Table 5.1). The most sensory-significant linolenate-derived aldehydes (with lower threshold values) were characteristic in having n-3 unsaturation. These trends explain why linolenic acid oils develop undesirable odors and flavors at much lower levels of oxidation (peroxide value of less than 1) than linoleic acid oils (peroxide value of 10). Similarly, potent volatile aldehydes have been identified in fish oil oxidized at very low levels of oxidation by static and dynamic headspace GC (see F.2) and detected by GC-MS at parts per billion levels, including cw-4-heptenal (1250 ppb), fran, cw-2,6-nonadienal (1231 ppb)andCiXcw-3,6-nonadienal(627 ppb). Cis-4-heptenal is produced by decomposition of fran, cw-2,6-nonadienal, which can be produced in turn by the decomposition of n-7 and n-9 hydroperoxides derived from the oxidation of 20 4, 20 5 and 22 6 n-3 PUFA (Chapter 4, D4). 

Cottonseed Oil. The B.P, modification of Halphen s test, in which the oil (2 5 g) and reagent (2-5 ml of equal volumes of amyl alcohol and 1 per cent precipitated sulphur in carbon disulphide) are heated under slight pressure, will detect less than 5 per cent of cottonseed oil and may be made roughly quantitative up to 20 per cent by the use of comparison mixtures. Kapok oil also gives this reaction, and fats from animals fed on cottonseed cake may show a slight positive test. The reaction is not given by oils which have been previously heated to above 200°. The amyl alcohol may be replaced by a drop of pyridine which is said to make the test more sensitive (Gastaldi24). 

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